Effect of Zn Addition on the Microstructure and Mechanical Properties of Cast Mg–10Gd–3.5Er– xZn–0.5Zr Alloys
来源期刊：Acta Metallurgica Sinica2020年第11期
论文作者：Qiu Zhang Wencai Liu Guohua Wu Liang Zhang Wenjiang Ding
文章页码：1505 - 1517
摘 要：In this work, the effects of Zn content（0–2 wt%） on microstructural evolution and mechanical properties of cast Mg–10 Gd–3.5 Er–0.5 Zr alloys are studied. The results show that the as-cast Mg–10 Gd–3.5 Er– x Zn–0.5 Zr alloys are mainly composed of Mg matrix and secondary（Mg, Zn）3（Gd, Er） phases distributed along grain boundaries. With the increase in Zn content, the volume fraction of secondary（Mg, Zn）3（Gd, Er） phases increases and the grains get refined. In the process of solid solution treatment, Zn addition can lead to the formation of long-period stacking ordered（LPSO） structures and the volume fraction of LPSO structures increases with Zn content. In addition, the Zn addition can reduce the vacancy formation energy and accelerate the diffusion rate of RE elements in Mg matrix. Because of the comprehensive effect of secondary phases and the accelerated diffusion rate, the base alloy and 2 Zn alloy have less grain growth after solid solution treatment than that of the 0.5 Zn alloy and 1 Zn alloy. The precipitation process is also accelerated by enhanced diffusion rate. At room temperature（RT）, the strengthening effect of β’ + β1 precipitates is more effective than that of LPSO structures, so the peak-aged 0.5 Zn alloy exhibits the most excellent mechanical performance at RT, with yield strength of 219 MPa, ultimate tensile strength 296 MPa and elongation of 6.4%. While LPSO structures have stronger strengthening effect at elevated temperature than that of β’ + β1 precipitates, so the 1 Zn alloy and 2 Zn alloy have more stable mechanical performance than that of the base alloy and 0.5 Zn alloy with the increase in tensile temperature.
Qiu Zhang，Wencai Liu，Guohua Wu，Liang Zhang，Wenjiang Ding
National Engineering Research Center of Light Alloy Net Forming and Key State Laboratory of Metal Matrix Composites, School of Materials Science and Engineering , Shanghai Jiao Tong University
摘 要：In this work, the effects of Zn content（0–2 wt%） on microstructural evolution and mechanical properties of cast Mg–10 Gd–3.5 Er–0.5 Zr alloys are studied. The results show that the as-cast Mg–10 Gd–3.5 Er– x Zn–0.5 Zr alloys are mainly composed of Mg matrix and secondary（Mg, Zn）3（Gd, Er） phases distributed along grain boundaries. With the increase in Zn content, the volume fraction of secondary（Mg, Zn）3（Gd, Er） phases increases and the grains get refined. In the process of solid solution treatment, Zn addition can lead to the formation of long-period stacking ordered（LPSO） structures and the volume fraction of LPSO structures increases with Zn content. In addition, the Zn addition can reduce the vacancy formation energy and accelerate the diffusion rate of RE elements in Mg matrix. Because of the comprehensive effect of secondary phases and the accelerated diffusion rate, the base alloy and 2 Zn alloy have less grain growth after solid solution treatment than that of the 0.5 Zn alloy and 1 Zn alloy. The precipitation process is also accelerated by enhanced diffusion rate. At room temperature（RT）, the strengthening effect of β’ + β1 precipitates is more effective than that of LPSO structures, so the peak-aged 0.5 Zn alloy exhibits the most excellent mechanical performance at RT, with yield strength of 219 MPa, ultimate tensile strength 296 MPa and elongation of 6.4%. While LPSO structures have stronger strengthening effect at elevated temperature than that of β’ + β1 precipitates, so the 1 Zn alloy and 2 Zn alloy have more stable mechanical performance than that of the base alloy and 0.5 Zn alloy with the increase in tensile temperature.
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